Repressed memories are memories that have been unconsciously blocked due to the memory being associated with a high level of stress or trauma. The theory postulates that even though the individual cannot recall the memory, it may still be affecting them subconsciously, and that these memories can emerge later into the consciousness. Ideas on repressed memory hiding trauma from awareness were an important part of Sigmund Freud's early work on psychoanalysis. He later took a different view.
The existence of repressed memories is an extremely controversial topic in psychology; although some studies have concluded that it can occur in a varying but generally small percentage of victims of trauma, many other studies dispute its existence entirely. Some psychologists support the theory of repressed memories and claim that repressed memories can be recovered through therapy, but most psychologists argue that this is in fact rather a process through which false memories are created by blending actual memories and outside influences. One study concluded that repressed memories were a cultural symptom for want of written proof of their existence before the nineteenth century, but its results were disputed by some psychologists, and a work discussing a repressed memory from 1786 was eventually acknowledged, though the others stand by their hypothesis.
According to the American Psychological Association, it is not possible to distinguish repressed memories from false ones without corroborating evidence. The term repressed memory is sometimes compared to the term dissociative amnesia, which is defined in the DSM-V as an "inability to recall autobiographical information. This amnesia may be localized (i.e., an event or period of time), selective (i.e., a specific aspect of an event), or generalized (i.e., identity and life history)."
According to the Mayo Clinic, amnesia refers to any instance in which memories stored in the long-term memory are completely or partially forgotten, usually due to brain injury. According to proponents of the existence of repressed memories, such memories can be recovered years or decades after the event, most often spontaneously, triggered by a particular smell, taste, or other identifier related to the lost memory, or via suggestion during psychotherapy.